Selenium rectifier having an insulating layer



SELBNIUM RECTIFIER HAVING AN INSULATING LAYER Filed May 26, 1957 5450mm 77m; HATER/AL Lew/21M ELECTROE ELECTR DE JELLW/UM TIA/6 SELE/VIUM CARRIER ELECTRODE Ihventdr: Fritz Brunke ttorney.

Patented Sept. 24, 1941) UNITED STATES.

PATENT OFFICE SELENIUM RECTIFIER HAVING AN INSULATING LAYER Fritz Brunke, Berlin-Steglitz, Germany, assignor to General Electric Company, a corporation of New York Application May 26, 1937, Serial No. 144,967

- In Germany June 13, 1936 7 Claims.

My invention relates to dry plate rectifiers, and like devices such as light-sensitive cells, of the selenium type, and particularly to methods of treating selenium rectifier elements and the like whereby a more uniform product is obtained.

In the process of manufacturing rectifiers and light-sensitive cells of the selenium type a base or carrier electrode of a suitable metal is coated with a semi-conductor layer formed of selenium or a selenium compound, and after proper heat treatment a counter electrode, functioning as a conductor of the current which flows through the semi-conductor layer and the bearer electrode,

applied to the semi-conductive layer. In the course of tests during the manufacture of such devices it has been found that a gas layer, which is produced during the manufacturing process and adsorbed on the selenium semi-conductor layer on that surface thereof to which the counter electrode is applied, has played an important role in obtaining trouble-free operation of the rectifier.

Difficulties have been encountered, however, in

the practice of the method of manufacture which includes the above-described adsorption of a gas layer on the selenium semi-conductive layer. From the above-mentioned tests it has been found that in the process of manufacture of the selenium rectifier elements it is not possible arbiao trarily for such gases to be produced always in the same form. In accordance with my present invention the foregoing difiiculty is obviated in that the adsorbed gas layer is dispensed with, being replaced by an insulator which is formed by a process permitting control of the insulator thickness within close limits.

My invention will be better understood from the following description when considered in connecticn with the accompanying drawing and its scope will be pointed out in the appended claims.

Referring to the drawing, Figs. 1 and 2 illustrate selenium rectifier or like cells or elements in which layers of insulating material in accord-= ance with my invention have been incorporated.

$5 In Fig. l the rectifier cell or element comprises a base or carrier electrode l, a semi-conductor layer 2 of selenium or selenium compound on the carrier electrode, and a counter electrode 3. In accordance with the present invention, prior to the application of the counter electrode 3 to the semi-conductor. layer 2 a thin layer l of an insulating material is appliedto the layer 2, or the layer l may be applied to the counter electrode 3 and the application of the counter electrode to 5 the semi-conductor layer 2 may then be made, in

such manner that the insulating layer 4 is in contact with the semi-conductor layer.

The insulating layer is of such order of thickness as not to prevent proper flow of current through the rectifier cell. Preferably the thickness is of the order of 10- cm. or in certain cases less than 10- cm. In accordance with the invention the layer is preferably applied by exposing the semi-conductor layer 2 or the counter electrode 3 to a vapor of a metal to form a compound of selenium. I have found that by the vaporization method of applying the insulating layers the thickness thereof may be controlled with precision. The vapor of various metals may be employed in the above-described process. I have found, however, that in the manufacture of selenium rectifiers by the present process a non-conducting modification of selenium such as the amorphous form of selenium or a non-conducting compound of selenium is a preferable material for the insulating layer. Fig. 2 illustrates a rectifier cell in which the semi-conductor layer is of the conducting modification of sele nium as in Fig. 1, but the insulating layer, 5, is 25 formed of a non-conducting selenium such as the amorphous form or of a non-conducting selenium compound.

My invention has been described herein in particular embodiments for purposes of illustration. It is to be understood, however, that the invention is susceptible of various changes and modifications and that by the appended claims I intend to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A dry plate element including a carrier electrode, a layer on said electrode composed of the conductive form of selenium, a counter electrode, and a layer of the non-conductive form of selenium on said counter electrode and in contact with said first-named layer.

2. A dry plate element including a carrier electrode, a layer on said electrode composed of the conductive form of selenium, a counter electrode, and a layer of the non-conductive form of selenium less than 10- cm. in thickness on said counter electrode and in contact with said firstnamed layer.

3. The method of producing a dry plate element having a counter electrode and a semi-conductor layer composed of a material of the group comprising selenium and selenium compounds, which includes applying to said semi-conductor layer prior to the application thereto of said counter electrode a thin layer of an insulating material by vaporization of said insulating material, said material consisting of the non-conducting form of selenium.

4. The method of producing a dry plate element having a semi-conductor layer composed of a material of the group comprising selenium and selenium compounds, which includes exposing said semi-conductor layers to the vapor of an insulating material to form a layer of said insulatingmaterial of less than 10- cm. in thickness on said semi-conductor layer, said material consisting of the non-conducting form of selenium.

5. The method of producing a dry plate element having a semi-conductor layer composed of a material of the group comprising the conductive modification of selenium and conductive selenium compounds, which includes applying to said semi-conductor layer a thin layer of the non-conducting modification of selenium by vaporization thereof.

6. A dry plate element including a carrier electrode, a semi-conductor layer on said electrode composed of a material oi! the group comprising selenium and selenium compounds, 8. counter electrode, and a layer of insulating material on said counter electrode and in contact with said semi-conductor layer, said insulating material cpnsisting of the non-conducting form of selenium.

'7. A dry plate element including a carrier electrode, a semi-conductor layer on said electrode composed of a material of the group comprising selenium and selenium compounds, a counter electrode, and a layer of insulating material less than 10- cm. in thickness on said counter electrode and in contact with said semi-conductor layer, said insulating material consisting of the non-conducting form of selenium.

FRITZ BRUNIQB. 

